1. Field
A flexible wiring board for a magnetic head assembly is provided.
2. Related Art
A typical magnetic head assembly comprises a flexible wiring board for conductively connecting a head body (magnetic head slider) fixed to a free end of the magnetic head assembly to a circuit system provided outside the head assembly. The flexible wiring board generally includes a wiring pattern having one end connected to the head body and the other end connected to the external circuit system, an insulation protection film for protecting the wiring pattern, and a metal base material provided over the insulation protection film and the wiring pattern. The flexible wiring board is fixed to the magnetic head assembly such that an intermediate portion of the flexible wiring board in the longitudinal direction thereof is bent perpendicularly. Examples of such a flexible wiring board are disclosed in Japanese Unexamined Patent Application Publication Nos. 2000-48339, 2000-331323, 2001-111178, and 2004-335042 (U.S. Patent Application Publication No. 2004/0228038A1).
In known structures, when the flexible wiring board is bent perpendicularly, a bending stress is concentrated at a part of the bent portion and there is a risk that cracks will form in the insulation protection film. The insulation protection film is composed of insulating resin material, such as polyimide, and the risk that cracks will form is increased as the mechanical strength of the insulation protection film is increased in order to ensure the protection of the wiring pattern. Cracks in the bent portion can be prevented by reducing the concentration of bending stress in the flexible wiring board.